The present invention relates to packaging for electrophoresis gels and, more particularly, to an improved vacuum sealed package combination for containing and protecting electrophoresis gels during storage, handling and shipment.
Most biological macromolecules are electrically charged such that, when subjected to an electrical field, they begin to move, This phenomenon is the basis behind an electrophoresis process wherein a prescribed electrical current is generated adjacent to a collection of macromolecules to produce movement of the macromolecules through a solvent in a particular direction. Since different macromolecules vary in molecular size, weight and charge, it is possible to use an electrophoresis process to distinguish between different macromolecules based on their respective rates of movement through the solvent. Electrophoresis can also be used for other types of macromolecule analysis, such as detecting amino acid changes, nucleic acid sequencing and protein analysis.
One medium that has been used for over thirty years as the carrier for the macromolecules in an electrophoresis process is a gel. Two of the most popular types of gels are agarose and polyacrylamide gels. An electrophoresis gel is typically planar in shape and includes a series of spaced apart wells. The wells are designed to receive the biological sample being tested. In the past, it was customary for the laboratory that was conducting the testing to cast their own gels by hand. It soon became apparent, however, particularly as electrophoresis testing of DNA increased, that it is more convenient and more precise to use precast gel slabs made to uniform composition, size and well configuration standards.
Conventional gels are made from various materials depending on their intended use. One widely used gel material for DNA electrophoresis is agarose. This gel is a sugar based gel that is highly flimsy and subject to tearing and deformation if not handled carefully. Tearing or cracking is especially prone between the wells where the least amount of material is present. Deformation or tearing of the gel can potentially produce inaccuracies during testing. To complicate matters further, the material properties of the gel make detecting hairline cracks very difficult. Hence, proper packaging of the gels is extremely important when shipping or storing the gels.
Several packaging arrangements have been developed in recent years to protect electrophoresis gels during shipment. U.S. Pat. No. 5,443,704 discloses one packaging arrangement for protecting the gels. This packaging arrangement includes a plastic tub within which the gel is placed. A foil-lined cover is adhered to the top of the tub to retain moisture inside the package. It was subsequently determined that the tub alone did not provide sufficient protection for the gel. Filler materials had to be added to the box to provide adequate protection from damage. As a result, this type of packaging arrangement is generally very expensive to produce.
Another prior packaging arrangement for shipping gels includes a pouch formed from foil material that is sealed along each edge. In order to protect the gel, a separate sheet of material is folded over the gel to separate it from the foil. A deficiency with this packaging arrangement is that the package does not adequately protect the gel from damage such as edge deformation and well breakage.
U.S. Pat. No. 5,837,288 discloses one particular type of pouch wherein the pouch is almost completely evacuated of air prior to sealing, resulting in a reduced atmospheric environment (i.e., less than 10% of atmospheric air pressure). Spacers are used on the sides of the gel to prevent the package walls from crushing the sides of the gels.
Co-pending patent application Ser. No. 09/177,469, entitled xe2x80x9cVacuum Package for Electrophoresis Gelxe2x80x9d, filed Oct. 23, 1998, discloses an alternate package configuration which, in one embodiment, uses a support sheet in combination with a sealed, at least partially evacuated interior to restrain the gel within the package for preventing gel damage during storage and shipping.
A need exists for an improved packaging arrangement which is inexpensive to manufacture and which adequately protects a gel or series of gels from damage during shipment, handling or while stored.
An object of the invention is to provide a package for an electrophoresis gel which includes sufficient rigidity to prevent damage to the gel and minimize movement of the gel within the package. The wells in the gel make it particularly susceptible to damage and breakage during shipment.
Another object of the invention is to provide a package for an electrophoresis gel which, in one embodiment, includes a support tray that functions as part of the packaging during shipment and can be subsequently used to hold the gel during an electrophoresis process.
These and other objects and advantages of the invention are provided by the packaging arrangement according to the present invention. The packaging arrangement includes first and second sheets that are sealed along their respective edges to form an enclosed cavity. In one embodiment, the cavity is at least partially evacuated of air prior to or after sealing. At least one electrophoresis gel is disposed within the evacuated cavity. The partial evacuation of air from the cavity causes the top and bottom sheets to conform to the gel, thereby restraining it from movement within the package.
In one embodiment of the invention, a tray is incorporated into the package. The gel is located within the tray which, in turn, is located between the top and bottom sheets. The tray includes a base and at least two side walls which extend upward along the longitudinal sides of the gel. The combination of the low pressure environment in the package and the tray produces a rigid packaging configuration that minimizes motion of the electrophoresis gel contained therein.
The foregoing and other features and advantages of the present invention will become more apparent in light of the following detailed description of the preferred embodiments thereof, as illustrated in the accompanying figures.